JPH04271290A - Drive controller - Google Patents

Abstract

PURPOSE:To eliminate synchronization error between respective shafts at the time of acceleration or deceleration, when a plurality of shafts are operated synchronously, by eliminating the difference between a position command X* and a position XL at the tip of machine which occurs upon acceleration or deceleration of motor. CONSTITUTION:The drive controller comprises a motor 10, a machine load 12, a first adder 34, a second adder 42, a third adder 46 and a fourth adder 50. Secondary derivative of a position command is multiplied by a predetermined coefficient and added through the first adder 34 to a torque command value. The sum is then multiplied by a predetermined coefficient and added through the second adder 42 to the position command as a position correcting value. Primary derivative of the position command corrected value is multiplied by a predetermined coefficient and added, as a speed correction value, to the speed command value through the third adder 46. Furthermore, secondary derivative of the position command correction value is multiplied by a predetermined coefficient and added, as a torque correction value, to a torque command value through the fourth adder 50 thus eliminating the difference between a position command X* and the position XL at the tip of machine upon acceleration or deceleration thereof.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention comprises a mechanical load driven by a motor and an encoder that detects the rotational position of the motor, and calculates a speed command value and torque from the detected position of the motor detected by the encoder and the position command. The present invention relates to a drive control device that controls the position and speed of a mechanical load by deriving a command value and controlling the input current of a motor.

0002

[Prior Art] Conventionally, a machine is equipped with a mechanical load driven by a motor and an encoder that detects the rotational position of the motor.
A drive control device is known that controls the position and speed of a mechanical load by deriving a speed command value and a torque command value from a motor detection position detected by an encoder and a position command, and controlling the input current of the motor. As shown in FIG. 4, this drive control device includes a mechanical load 12 driven by a motor 10, an encoder 14 that detects the rotational position of the motor 10, and a mechanical load 12 that is detected by the encoder 14.
and a drive control section 16 that controls the position and speed of. Then, the drive control unit 16 outputs a position command X*
A subtracter 18 that subtracts the detected position X detected by the encoder 14 from
a multiplier 20 for multiplying by a gain coefficient Kp of the position loop;
First derivative of position command X* with respect to time (X*)'
a differentiator 22 for calculating the speed command V* by adding the first derivative (X*)' calculated by the differentiator 22 and VDiff calculated by the multiplier 20, and an adder 24 for calculating the speed command V*.
A subtracter 28 calculates a speed deviation ΔV by subtracting the result of differentiating the detected position The first derivative (X*
)′ and multiplies it by a predetermined coefficient Kj, and an adder 34 that adds the output Kj(X*)″ of the differentiator 32 and the output of the proportional-integral amplifier 30 to obtain the torque command T*. , the torque command T* calculated by the adder 34
and a current command calculation unit 36 that calculates a three-phase current command i* based on the detected position X detected by the encoder 14, and a current supplied to the motor 10 based on the three-phase current command i* calculated by the current command calculation unit Inverter 38 that controls
It is composed of.

Next, the operation will be explained. Position command X*
is an encoder 14 that detects the rotational position of the motor 10.
is input to the subtracter 18 together with the detected position X, and the positional deviation Diff is determined. And the positional deviation Dif
f is input to the multiplier 20 and multiplied by the position loop gain coefficient Kp to become VDiff. On the other hand, the differentiator 22
The first derivative of position command X* with respect to time (X*
)' is determined, and the first derivative (X*)' and VDiff are inputted to an adder 24 and added to form a speed command V*. Further, from the speed command V*, a speed deviation ΔV is obtained by subtracting the result of differentiating the detection position X detected by the encoder 14 using a differentiator 26 using a subtracter 28. Also,
First derivative of position command X* with respect to time (X*)'
The acceleration component is determined by the differentiator 32 and multiplied by a predetermined coefficient Kj to become Kj(X*)''.On the other hand,
The speed deviation ΔV is proportionally and integrally amplified by the proportional-integral amplifier 30, and the output of the proportional-integral amplifier 30 is added to the output Kj(X*)'' of the differentiator 32 by the adder 34 to obtain the torque command T*. The command T* is input to the current command calculation unit 36, and the current command calculation unit 36 calculates a three-phase current command i* based on the torque command T* and the detection position X detected by the encoder 14, and outputs it to the inverter 38. and controls the current flowing from the inverter 38 to the motor 10.As described above, the position X of the motor 10 and the position command X* are feedback-controlled so that the position deviation Diff becomes "0", and as a result, the The position X' of the mechanical load connected to follows the position command X*. In addition,
The predetermined coefficient Kj of the differentiator 32 is the total value JM of the inertia JM of the motor 10 and the inertia JL of the mechanical load 12.
+JL is selected. In addition, the motor 10 and the mechanical load 12
is a completely rigid body, the transfer function from the input of the current instruction calculation unit 36 to the output of the encoder 14 is (1/
JM + JL ) (1/S2 ), and the differentiator 22,
The transfer function connected in series with 32 is as follows, S・KjS・(1/JM +JL)(1/S2)=
Kj/JM +JL = 1... (1) When there is no disturbance, positional deviation Diff does not occur.

0004

The conventional drive control device is constructed as described above, and when the mechanical load 12 driven by the motor 10 is the drive system for the table 52 as shown in FIG. The position X of the motor 10 and the position XL of the table 52 do not dynamically match. By using a low sliding resistance mechanism such as a linear guide for the guide surface that directs and guides the table 52, the deviation between X and X' when the table 52 is stopped can be suppressed to a submicron level. On the other hand, during acceleration, the acceleration of the table 52 reaches about 0.5G (gravitational acceleration), and a force of several 100 Kgf is applied to each part. Therefore, a deflection of several tens of microns occurs at the attachment portion of the motor 10 and the ball screw 56 to the bed 54, the attachment portion of the ball screw nut of the table 52, and the like. This amount of dynamic deflection poses a problem when synchronizing multiple axes, and causes unevenness on the cutting surface, especially when the headstock and tool rest of the movable axes are moved in parallel while cutting in a compound lathe. This amount of deflection is shown in Table 5.
Although it is possible to measure by attaching a detector such as an inductosin to 2, the response frequency of the position loop is insufficient to reduce the error by feedback during acceleration and deceleration. If the sliding resistance is assumed to be negligible here and the spring constant is assumed to be K to simplify the model, then FIG. 5 can be approximated by FIG. 6. Next, when this is expressed as a block diagram, it becomes as shown in Fig. 7, and when Fig. 7 is combined with Fig. 2, the position command
*The table position XL can be obtained from the block diagram of FIG. Next, from the block diagram in FIG. 8, position command
The transfer function F(S) from * to the table position XL is calculated as shown in the second equation.

[0005]F(S)=A/B...(2
) However, A=KjS2 +(Kp+S)(Kvp+K
vi/S) B=(JM +JL)S2 +(1+JL S2/
K) (Kp+S) (Kvp+Kvi/S)+JM ・J
L S4 /KHere, if the stiffness is infinite, that is, if the spring constant K is infinite, the transfer function is 1, and

[0006]

[Formula 1]

[0007]

[0008] However, although Kj = (JM + JL) position command X* and table position XL match, the problem is that the smaller the rigidity and the larger the load inertia JL, the more the transfer function deviates from 1 and the deviation becomes larger. was there.

Purpose of the Invention The purpose of the present invention is to eliminate the deviation between the position XL of the tip of the machine and the position command X* that occurs when the motor accelerates and decelerates, and when multiple axes are operated synchronously An object of the present invention is to provide a drive control device that does not generate synchronization errors between axes during acceleration and deceleration.

0010

[Means for Solving the Problems] A drive control device according to the present invention includes a mechanical load driven by a motor and a torque command value that adds a predetermined coefficient times the second derivative of a position command with respect to time to a torque command value. a second addition means for adding a predetermined coefficient times the addition value to the torque command value to the position command as a position correction value, and a predetermined coefficient times the first derivative of the position command correction value with respect to time. a third addition means for adding the second derivative of the position command correction value with respect to time to the speed command as a speed correction value, and a fourth addition means for adding a predetermined coefficient times the second derivative of the position command correction value with respect to time to the torque command value as a torque correction value; It is characterized by having the following.

[0011]

[Operation] The drive control device according to the present invention adds a predetermined coefficient times the second derivative of the position command with respect to time to the torque command value using the first addition means, and multiplies the added value to the torque command value by a predetermined coefficient. is added to the position command as a position correction value by the second addition means, and a predetermined coefficient times the first derivative of the position command correction value with respect to time is added to the speed command by the third addition means as a speed correction value. , the fourth addition means adds a predetermined coefficient of the second derivative of the position command correction value with respect to time to the torque command value as a torque correction value, and the input current of the motor is controlled by the torque command value, thereby reducing the mechanical load. Control position and speed.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Note that the same parts as those shown in FIG. 4 are given the same reference numerals, and their explanation will be omitted. As shown in FIG. 1, the drive control device multiplies the output Kj(X*)'' of the differentiator 32, that is, the torque TM*, by a predetermined coefficient Kl to obtain KlTM.
A multiplier 40 that outputs * and an output KlT of the multiplier 40
An adder 42 as a second addition means for adding M* to the positional deviation Diff calculated by the subtracter 18, and a multiplier 4
a differentiator 44 that differentiates the output KlTM* of 0; an adder 46 as a third addition means that adds the output (KlTM*)' of the differentiator 44 to the speed deviation ΔV calculated by the subtracter 28; 44 outputs (KlTM*)
a differentiator 48 that further differentiates ' and multiplies it by a predetermined coefficient Kt;
The output Kt(KlTM*)'' of the differentiator 48 is sent to the adder 3
4 is provided with an adder 50 as a fourth addition means for adding to the torque command T* calculated by No. 4. Note that the above-mentioned adder 34 is the first addition means. Assuming a mechanical system model as shown in Fig. 7, Fig. 1 becomes as shown in Fig. 2, the blocks are arranged as shown in Fig. 3, and the transfer function of machine position XL to position command F(S)
, the equation (4) is obtained.

[0013]F(S)=C/D...(4
) However, C=KjS2 +(1+KjKlS2)(
Kp+S) (Kvp+Kvi/S)+KjKlKtS4
D=(JM +JL)S2 +(1+JL S2
/K) (Kp+S) (Kvp+Kvi/S)+JM ・
JL S4 /K where Kj=JM +JL,Kj
Kl=JL/K, KjKlKt=JM ・JL/K
Kj, Kl, Kt are (5), (6), (7
), then Kj=JM
+JL
...(5) Kl=
JL/KKj=JL/K(JM+JL)...
(6) Kt=JM・JL/K
KjKl=JM ・JL /K (JM +JL)
・(JL /K(J
M + JL )) = JM … (7
) Expression (5), Expression (6) and Expression (7) as Expression (4)
When substituted into the equation, F(S)=1, and the position command X* and table position XL can be matched.

[0014]

[Effects of the Invention] As explained above, according to the present invention,
The second derivative of the position command with respect to time is multiplied by a predetermined factor as the first
A second adding means adds a predetermined coefficient times the added value to the torque command value to the position command as a position correction value. The third derivative is multiplied by a predetermined coefficient.
is added to the speed command as a speed correction value using the adding means,
The position of the mechanical load is determined by adding a predetermined coefficient times the second derivative of the position command correction value with respect to time to the torque command value as a torque correction value using the fourth addition means, and controlling the input current of the motor using the torque command value. Since the configuration is configured to control the rotation and speed, it is possible to predict the amount of deflection of the mechanical drive system that occurs when the motor accelerates or decelerates, and perform feedforward control. , it is possible to suppress synchronization errors between each axis during acceleration and deceleration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a drive control device to which the present invention is applied.

FIG. 2 is a block diagram showing a configuration in which a mechanical system of a drive control device to which the present invention is applied is modeled.

FIG. 3 is a block diagram that is a modification of FIG. 2;

FIG. 4 is a block diagram showing the configuration of a conventional drive control device.

FIG. 5 is a diagram showing a configuration in which a conventional drive control device is applied to a table-driving mechanical system.

FIG. 6 is a diagram showing an approximate model of FIG. 5;

FIG. 7 is a block diagram showing the configuration of the approximate model in FIG. 6;

FIG. 8 is a block diagram showing a configuration in which a mechanical system of a conventional drive control device is modeled.

[Explanation of symbols]

10 Motor 12 Mechanical load 14 Encoder 34, 42, 46, 50 Adder

Claims (1)

[Claims] Claim 1: A mechanical load driven by a motor, and an encoder that detects the rotational position of the motor, and a speed command value and a torque command value are derived from the motor detection position detected by the encoder and the position command, and the motor is In a drive control device that controls the position and speed of a mechanical load by controlling the input current of
a second addition means for adding a predetermined coefficient times the addition value of the first addition means to the torque command value to the position command as a position correction value; a third addition means for adding the function to the speed command as a speed correction value;
A drive control device comprising: fourth addition means for adding a predetermined coefficient times the second derivative to a torque command as a torque correction value.